Batman aka Bruce Wayne is one of the main characters in Doomsday Clock.
In the world of Watchmen, Batman is a fictional character created by Bob Kane and Bill Finger, first debuting in Detective Comics Issue #27 in 1939. He, along with the other fictional superheroes of DC Comics, are largely forgotten by the time Watchmen takes place due to the prevalence of actual costumed heroes in their world.
In the DC Universe, Batman is renowned as the world's greatest detective, and the second smartest man in the world behind Lex Luthor. He was a child when his parents were gunned down in front of him during an alleyway mugging by petty criminal Joe Chill. This incident led Bruce to dedicate himself to the pursuit of justice as a costumed hero. Inspired by a bat which broke through his window, he used his family fortune to reinvent himself as Batman, and quickly established a reputation as one of the most fearsome superheroes in the world.
He was investigating his nemesis, the Joker, when a temporal anomaly allowed Wally West to breach the Batcave. He told Bruce that time had been tampered with before being pulled away. Later, when looking to see if anything had been damaged, he found a mysterious button embedded in the wall. When Flash arrived later to explain the situation more clearly, Batman showed him the button, and revealed it was emitting a radiation signature unlike anything either of them had ever seen before. The two agreed to keep it private until they determined more concretely what it was they were dealing with.
The Button Edit
A year later, Batman was musing over the button in the Batcave before tossing it aside. When he did, it reacted with Psycho Pirate's mask and unleashed a temporal anomaly which temporarily allowed Batman to see an alternative version of his deceased father, from a universe where he died in the alley instead of his parents. He immediately called up Flash to meet with him, but was ambushed by the Reverse Flash, a time traveler with a vendetta against both the Flash and Batman. The two battled briefly before Batman was overwhelmed. Reverse Flash was then teleported away, only to reappear seconds later burning to death, with his final words being that he saw "God".
Flash and Batman treated his death as a murder investigation. Knowing of Thawne's time traveling abilities, they concluded that an indeterminate amount of time likely passed between his departure from the cave and his demise. Attempting to follow his trail using the Cosmic Treadmill, Batman and Flash were bombarded by images of the history of their universe throughout its various incarnations, before being thrust into the alternate timeline glimpsed by Batman earlier. Flash recognizes it as the Flashpoint, a timeline he accidentally created, and which should have been destroyed when he corrected his mistake. They meet with Thomas Wayne, Bruce's father and this universe's Batman, who tells his son to give up being a superhero as it only inflicts pain. At that point, the Flashpoint collapses, and Bruce barely escapes with Flash.
They come upon Reverse Flash attempting to reach the source of the button, and despite Flash's warnings, he succeeds. Upon arrival, he is met by Doctor Manhattan, who eradicates him and completes the temporal loop before retrieving the button. Batman and Flash are nearly lost in time, before being unexpectedly rescued by Jay Garrick, the Golden Age Flash.
Later, at Wayne Manor, Bruce watches as the Bat Signal is displayed over Gotham City, summoning him for duty, but he simply stands there, haunted by his father's words.
Panic in the Microverse! Edit
Batman later leads his personal Justice League on a rescue mission to find atomic physicist and superhero Ray Palmer in the Microverse, a dimension existing at the subatomic level of the universe. During this time, they discover that the Microverse is being hit by quantum storms emanating from something called the Ignition Point. Upon reuniting with Palmer, he reveals to Batman that the Ignition Point is a breach in the firmament of the universe, created when something tunneled its way into their reality from another. Batman correctly deduces this to be related to the button.
Doomsday Clock Edit
One year later, Batman is fending off threats in both his identities. Batman is among the many heroes who faces growing public discontent and distrust due to the prevalence of the Supermen Theory, a conspiracy theory positing that the majority of the world's metahumans are United States government agents. Batman, never a trusted figure to begin with, is immediately pounced upon. However, he continues his crusade against crime in defiance of growing calls for him to be taken into custody. Meanwhile, Wayne Enterprises is in a corporate war with LexCorp. as they race to unlock the secrets of the Metagene, the genetic anomaly which allows for the manifestation of superpowers. A series of poor business decisions taken by Wayne have shaken the Wayne Enterprises Board of Directors faith in their C.E.O and some are talking of selling the company to Luthor, which would not only give away their research, but also expose Wayne as Batman.
During a patrol, Batman is alerted to a tripped alarm in the Batcave, and returns to discover Rorschach II waiting for him. Baffled by the appearance of this mysterious figure, Batman demands an explanation, and Rorschach provides one in the form of his predecessor's journal. Curious, Batman reads the journal, though only makes it a few pages in before being interrupted once again by Rorschach. He offers him a place to stay while he combs through the journal. He finds it contents convincing and lining up with his previous investigations, but can also tell that Rorschach is not mentally sound, and locks him up in Arkham Asylum under the guise of helping him in order to make sure he is secure. He continues to meet with him in disguise, but divulges no further information before he escapes the Asylum.
Batman instead pursues Adrian Veidt, who accompanied Rorschach II. Aboard the Owlship and running from the police, the two have a heated exchange over their respective methods in crimefighting before Batman is tossed from the vehicle by Ozymandias's reckless maneuvers. He attempts to catch himself in the fall but is caught by anti-superhero protesters below and is mauled by the crowd before being captured by Joker's henchmen and brought before his nemesis.
He is escorted to a meeting of Gotham's underworld where the villains are discussing the growing global instability and the threat of a so-called Super War. Ironically, none of them believe Joker's actually captured Batman due to having pulled similar tricks on them in the past. They are interrupted by the Comedian, who opens fire in pursuit of Joker's other two captives, Mime and Marionette. Joker escapes with Batman, ambushes the Comedian and agrees to work with his former captives to find Doctor Manhattan.
During a torture session with Comedian, Batman breaks his restraints and engages the three clowns. Still badly beaten from his encounter with the protesters, Batman is unable to put up an effective fight against the three of them, but is saved by the arrival of Veidt and Rorschach, who Batman apologizes to. They summon Doctor Manhattan, but Batman and the Joker are left out of the loop as Manhattan teleports away with the other visitors. When they return, Batman watches an enraged Rorschach assault Ozymandias and Joker before taking off his mask and fleeing. Briefly inspecting to make sure that Joker is still alive, Batman grabs Rorschach's mask and goes after him.
When the U.S. Government attempts to launch a nuke, he breaks into a military facility to stop them.